| Plant communities are the foundation of forest ecosystem, also as important measuring indicators of the developing level in urban forest. Constructing a scientific and rational structure of plant communities help urban forest developing stably, efficiently and healthily. As a result, studying the plant communities of urban forest is significant for the city's sustainable development and the construction of an ecological city. Based on Xiamen, a coastal city,we chose 57 typical plant communitis as research objects.All of the communities were relativly steady among the primary parks,establishments,nature-approximating vegetations. First, we investigated and analyzed the floristic composition,the type,the ecological structure and the species diversity of every community, generalized the characteristics of the plant communities of Xiamen urban forest. Then, according to the geographical features and climatic conditions,according to the relevant research and the layout of green space in Xiamen, we did the fieldwork and collected the relevant datas about the current situation of urban forest,the scenic stand,the coastal shelterbelt system,the resource of mangrove,the regional culture and the custom tourism, and so on. We determined every modulus of air indicator. Suiting to local conditions, We ascertained the important value,actual value and target value through Delphi-method and the relevant literatures. The purpose of these values is not only to apply the evaluation of green space, but also to supply evidence for the layout,the developing pattern,the construction standard,the choice and disposal of plants,the land management and money raising of Xiamen. The main results are as follows:(1) In the 57 plant communities, there are 347 vascular plants belonging to 272 genera, 101 families, which occupy 60．48 percent in genera ,37．6 percent in species of the existing plants in Xiamen. The plants consist of 11 fern plants belonging to 9 genera in 8 families,6 gymnosperm plants belonging to 4 genera in 4 families,330 angiosperms plants belonging to 259 genera in 89 families. The plam contains the most species which are 32 belonging to 23 genera. The second most is euphorbiaceae, which includs 22 species belonging to 14 genera.(2) There are 277 arbors and shrubs in these 57 plant communities. The number of local plants is 57, which occupies 20．58 percent in all of the arbors and shrubs. The number of exotic species is 220, which occupies 79．42 percent, larger than the local plants. Analyzing the type of exotic species,we could conclude that the dominate plants of exotic species in Xiamen plant communities are evergreen arbors and ornamental shrubs.(3) The appearance of the existing vegetation in Xiamen is subtropical monsoon evergreen broad-leaved forest. Evergreen broad-leaved trees dominate the mixed stand, deciduous broad leaved trees and evergreen conifers are symbiotic. The evergreen-deciduous theropencedrymions and deciduous broad leaved forests are few. The frequency of deciduous broad leaved trees and evergreen conifers is too low.(4) Basing on the the relativity analysis and the principal component analysis of each type of plant community, We could conclude: There is much notable correlation among the structure factors. The main characteristics of communities focus on a few structure factors. But there are many notable diversities among the main factors which can describe the characteristics of the 3 different types of communities. The arbor's character of highth occupies the main position in park-style, the shrub's character of density occupies the main position in establishments-style, and all the characters of shrub occupy the main position in nature-approximating style. It shows that the 3 types of communities have their own features. At the same time, the positions of the notable relativity are similar which exists in the structure factors of the communities. It shows that there have an orderly relation among the structure factors of communities.(5) The abundance of species and the diversity index in park-style communities are higher than that of others. Ranging the sequence of the abundance of species and the diversity index in 3 types of communities, we could conclude: park-style > establishments-style >nature-approximating-style. Because of the different types and function,there are obvious differences in the structure of communities. Otherwise, the diversity indexs in the 8 park-style communities are different from each other for the different area,different function and different constructing time.(6) Urban green space ecological evaluation system are not only called for incarnating the comprehensive benefits,the ecological function and the aesthetic function of the whole urban green space system, but also called for high operability. At the same time,we must establish various kinds of evaluation indexs according to the various natural landscape,geographical terrain and the region's cultural characteristics, in order to accuratly and objectively incarnate the reality of the city's green space constructions. According to the south subtropical characteristics of Ximen which is esay to be attacked by typhoon, We set up a binary evaluation index-system in this article. |
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